If you are on a desktop, merely take your mouse, hover over the palette, and scroll down.

If you are on a Mac, hover over the palette, and use two fingers on the mouse pad to scroll down.

If you are on a PC Laptop, check and see if there is a line on a side of your mouse pad. You should be able to use that to scroll. Should you not see that, you can use Anach's CASSkin6x4 Mod with can be found here.